Misfiring, loss of power, popping. Where to start?

[94' Five.0]

Hey folks, I've got an issue and I'm really not sure where to start. I'm hoping to narrow down the possible culprits before I just start replacing parts.

The main problem is limited to the right side. There is hesitation and a loss of power with popping in the right exhaust during acceleration between 2nd and 3rd gear. The problem isn't present at idle though I've noticed some very random idle surging at times. The popping isn't constant after the car warms up but the hesitation is still there.

While checking for vacuum leaks I found a rotted line from the intake to the canister purge regulator. Replacing the line didn't solve the problem but it did seem to make the idle a little stronger. The plugs, distributer cap/rotor, and plugs were replaced about 4-5 years ago. I'm still using the original wires and coil. When I started checking the ignition system I noticed a funny reading on the coil. The secondary resistance is within spec but the primary is reading virtually no resistance. Enough that it is triggering the continuity tone on my DMM. So I'm not sure if this means the coil is bad or not. The coil terminal and connecting wire looks pretty corroded and misshaped. I pulled codes and I'm getting 172 and 173, which means the right O2 sensor is faulting lean and rich.

Could a bad O2 sensor cause this problem or even the coil? I'll probably end up changing all the plugs again and maybe the wires (though they still look pretty good minus the coil wire). Has anyone run into this type of problem before and found a fix?

Thanks

 

[HISSIN50]

Were codes cleared after the vac line was fixed?

It sounds like the coil has seen better days. I'd probably replace it for the sake of doing so. I like keeping a used coil in my trunk as a spare, so you could do that with your old one (for a limp-home if needed).

You can switch the O2's and see if the code chases that particular sensor or if it stays on that side of the engine.

Good luck.

 

[94' Five.0]

Were codes cleared after the vac line was fixed?

Ahh good catch, I completely forgot to clear them after fixing the line. I went out this afternoon, cleared the codes, and drove the car for about 45 min.

I didn't see the CEL come on again, but 45 min is a pretty quick test. However the light had been switching on and off pretty frequently during short drives before.

The hesitation and popping was still there though. Since its only on one side I'm not sure if the problem is the coil or not. However its condition would warrant a swap anyway. Maybe its an injector, plug, or wire issue.

 

[BlackVert]

i'd check the spark plug wires

 

[94' Five.0]

The CEL came back on today and I pulled code 173 by itself this time. Im guessing its an ignition problem since the right bank is reading rich? I'm running all stock ignition and fuel systems. I pulled the wires and tested them with a DMM. I didn't notice any irregular measurements and there wasn't any sign of burns or splitting. The cap and rotor button looked to be in good order.

Aside from replacing all the plugs, wires, cap/rotor, and coil is there any sensors I'm overlooking that could cause this?

 

[HISSIN50]

If it was me, I'd swap the O2's around.

I'd also mist the wires with water from a spray bottle at night. This is a nice dynamic test (stuff can ohm-out ok but once you ram a zillion volts through it, it leaks like a sieve). Be careful of moving parts under the hood and all that.

If you think you have a slight miss, you can run a cylinder balance test. This will atleast give you a cylinder to look at.

Good luck.

 

[Adam95GT]

If it was me, I'd swap the O2's around.


Good luck.

Bingo... I had this same problem same code... faulty 02... they can cause tons of stupid problems

 

[94' Five.0]

Small update...after new plugs, wires, cap/rotor, clean MAF, and flooding the Dist bowl, the popping seemed to have vanished. I still noticed some random hesitation and the lean code for the right O2 sensor was still present.

I replaced the O2 sensors today and so far so good. The CEL hasn't come back on and I haven't noticed the miss on the right side yet. I'm keeping my fingers crossed and hoping it was just the sensor all along.

Now on to the oil leaks